Aimed at the non-contact color measurement of Dunhuang mural pigment, by taking reference from the spectroscopic data of contact color measurement devices, non-contact device PR705 for spectral radiosity was used to measure the spectroscopic data of Dunhuang murals with the condition of different illumination and measure distances. The calculated RMS and E of the color charts with different illumination and measure distances were used as the parameters for evaluation, the functional relationship between them was obtained by optimal fitting. The effects of measure distance and illumination on accuracy of pigment measurement were analyzed in order to realize the optimization of measuring condition and enhance the measurement accuracy. The results showed that performance of measurement accuracy was optimal when measurement distance was in the range of 0.5~1.0 m and 2.0~2.5 m, with the illumination distance in the range of 3.0~3.5 m, while the RMS and E reached the minimum, with RMS less than 0.006, E less than 0.5.